#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>


/**
 * 
 * 判断否是完全图
 * 
 */
int main() {
	const int MAX_NODES = 110;
	int graph[MAX_NODES][MAX_NODES]{};

	int n, m;
	scanf("%d%d", &n, &m);
	for (int i = 0; i < m; i++) {
		int u, v;
		scanf("%d%d", &u, &v);
		graph[u][v] = 1;
		graph[v][u] = 1;
	}

	
	for(int i=1; i < n; i++) {
		for (int j = 1; j < n; j++) {
			if (i != j && graph[i][j] == 0) {
				printf("No");
				return 0;
			}
		}
	}

	printf("Yes");

	return 0;


}